The problems of scale deposition, corrosion, and attendant effects, such as pitting, have troubled water systems for years. For instance, scale tends to accumulate on internal walls of various water systems, and thereby materially lessening the operational efficiency of the system. In this manner, heat transfer functions of the particular system are severely impeded.
Water systems often have cooling water systems for cooling a water stream to a lower temperature and rejecting heat to the atmosphere. Cooling water towers may use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature, or may rely solely on air to cool the working fluid to near the dry-bulb air temperature in the case of a closed circuit dry cooling tower. Evaporation rates vary with changes in ambient wet bulb temperature, and thus contributes to water gains and losses during the cooling tower operation.
The formation of scales and/or deposits in industrial water systems may be inhibited by using water soluble polymers. However, using such water soluble polymers as anti-scalant or dispersant may be highly dependent on the concentration thereof. If too small of a concentration of the polymer is added to the water system, scaling and deposition will occur. On the other hand, if too large of a concentration of the polymer is added to the water system, the cost and performance efficiency of the water system may be adversely affected. With other methods of chemically treating aqueous systems, there is an optimal concentration of treatment chemicals to be maintained. Because of the desire to optimize the concentration of the polymer, determining the concentration of the polymers may be beneficial.
There are several methods of determining the concentration of water soluble polymers in aqueous water systems, such as but not limited to colorometric approaches (e.g. Hach polyacrylic acid method that uses thiocyanate chelation to detect calibration based on polyacrylic acid). However, these methods typically require a complicated, multi-step operation procedure and are difficult to carry out in the field. Turbidity method relies on the formation of insoluble compounds in determining the concentration of water soluble polymers. This method is lengthy and quite often susceptible to inaccuracies.
Since there are a lot of unknown variables and unknown volumetric changes inherent to cooling tower systems, there were also attempts to automate the precise addition of chemicals to cooling waters. Several technologies were patented by adding a fluorescent tag to cooling waters. Those technologies focused on measuring the amount of fluorescent tag to the system and correlate this amount to the concentration of the scale inhibitor. However, since a lot of factors affect the behavior of the fluorescent tag in the system (e.g. interaction of the fluorescent tag and the available scale inhibitor; interaction of the fluorescent tag to the scale formed, interaction of the fluorescent tag to the different water chemistry) that could interfere with the fluorescence reading, there is an ongoing need for the development of improved methods of monitoring and controlling the concentration of water treatment agents in cooling water systems.
Thus it would be desirable if methods and aqueous systems could be devised that decrease scale, yet enable a person or user to determine the actual concentration of these water soluble polymers in the chemical treatment of aqueous systems. It would also be desirable to have a simple method for detecting the water soluble polymers that has a decreased response to interferences, and where the method may be conducted on-site.